There is a fabulous Pyracantha free standing hedge on the side of a road we often drive along.near to Bridgemere Garden Centre, so I suppose that it is possible. Problem as far as I can see is that it is terribly prone to Fireblight, so could succumb if there is any in the area,

Very large aphids which are slightly on the grey side and found on Lupins could be American Lupin aphids. We had to give up growing these plants because we never could get rid of the pests and the plants did not thrive. We don't spray either, but I think in this case I would use an eco-friendly insecticide, say something like a plant based horticultural soft soap.

The Phlox subulata in our garden covers a mile a minute as our soil is well drained, but rich. Oakington Blue eyes is very robust, as is one of the red ones. Admittedly some of the others are slower growing hummocks.

They have survived all the weather can throw at them here and while in Winter they tend to look a bit bedraggled, they soon green up in Spring.

I grow the A.melanocarpa one and that is in dry ground. Our soil is well drained, neutral, silt and the berries are very good. Not edible straight from the bush as the seeds contain high levels of cyanins which give them their common name of Chokeberry. The juice is nice though, if slightly tannic.

Not sure why your is wrong, it could be the shrub itself is not healthy rather than the situation.